Hydrostatic pressure release. I have a concrete pool that is 50 – 60 years old. It is 20 ft x 40 ft x 10 ft deep. I live in New Orleans. We are known for fairly high water tables. The pool needs replastering. I was going to do it with Sider Oxydro’s Sider Proof FF-PR paint on, trowel over plaster resin product. I have only drained the pool once while we have lived here. Start to finish it was two days. Drained, pressure washed, filled. I am concerned about popping or floating the pool. I figure it will be empty about 5 – 7 days to get it cleaned, plastered, dry to fill. The pool piping is copper. I don’t know, but doubt there is a hydrostatic plug in the bottom drain. I have been told I either need to bust a big hole in the bottom, drill 6 – 8 .5 inch holes in the bottom, or bust a hole and put in a hydrostatic drain fitting.
Do I need to do this? If I bust a hole, or drill holes, when to I patch them and with what? It seems to me I need to patch and then plaster them, so they would still be closed off for 3 -4 days.
How should one do this? Is there a drain fitting I can install to hook a pump directly too? If so how? What type of pump etc?
Any input is greatly appreciated.

You should be very cautious about draining your pool especially this time of year when water tables are high. Floating the pool can become catastrophic. Hydrostatic pressure relief valves have been around that long but theres no telling who or what has been done to the pool since it was built. Diving the pool and removing the drain cover and looking for a flat round brass or plastic plate would the best place to start. If you find one, see if you can lift it up and if so you should be protected. The early ones didn't have orings.

Thanks. The pool is a little green right now, so I am not sure diving will work. Can relief valve be installed in the bottom of the pool once it is drained? Is sounds more reuseable than drilling holes.

Installing it after its drained might be too late! A pool built that long ago could have a 12-24 inch thick floor and you would have to core drill at least a 2 inch diameter hole. There is a good chance one was there originally and you just need to locate it. It might have been replaced with a plug at some point. You need to clear the water enough to dive down and see what you have before draining the pool. If you float the pool you can kiss away a huge amount of money to repair it.

I would be surprised if there wasn't a plug in the drain's bottom.

Scott

OK, Thanks. Looks like I need to do some drain and fill till I can get it clean enough to get in there and see. Will start with that. Otherwise I guess it is best to just drill holes? How and when to they get patched?

Plastering is a very specialized skill. This isn't a DIY job. It takes a skilled crew of at least 5 people to operate the mixer, pump nozzle, trowelers and supervisor. They should have pop-up insurance too.

Scott

I can vouch for sider oxy- it is great stuff i used my Mexican plaster guys to do my home pool and they knocked it out in 4.5 hours and it looks sharp- this is my second season with the pool and im so glad i used the sider oxy product- i paid my guys thoer standard rate of pay of 125/ day and got an exceptional look...i can send pics of the process if you want.
dave / Texas

In certain parts of the country, high water tables create many issues when remodeling a swimming pool; and as mentioned several times here above, 'floating' can be a very costly mistake. More recent swimming pools should contain a relief valve in the main drain. If the valve is not present, a common practice is to drill 'weep holes' in the bottom to allow ground water to enter the pool and relieve the pressure against the shell.

If you have not remodeled your pool yet, you are welcomed to contact me via private message to discuss your choice of finishes.

You could also look into well pointing around your pool this might be an option for you